Structural substrates for panels are generally formed of compression molded fibrous webs which are cut and molded into the shape required. Such substrates are used to back up interior paneling members, such as door panels and the like within automobiles and for other analogous uses. In the current methods of manufacturing the web material, which is later cut and compression molded, it is conventional to mix together fibers of wood and synthetic plastic which are distributed, by means of conveyor belts and suitable distribution rollers, and the like into non-woven fiber mats. A powdery, synthetic resin molding compound is applied to such mats. The mats are then heated to partially cure the molding compound. This gives the resulting web sufficient structural integrity so that it may be picked up, handled, moved about and positioned within mold cavities. Since the resinous material is only partially cured, a substantial portion of it remains uncured. That uncured portion is cured during the compression molding process by the application of heat and pressure to the material while it is contained within a cavity type of mold.
In the foregoing procedure, the partially cured resinous molding powder tends to form a skin-like crust on the surfaces of the web as well as relatively hard portions within the web so that the web resists easy flexing. Consequently, the web is more difficult to drape within the mold cavity around irregular mold areas, especially those areas which have relatively sharp corners or straight or undercut walls and the like. In addition, such materials are difficult to deep draw because of their relative stiffness and resistance to draping.
Moreover, in such prior procedure, since the resinous material used is partially cured before the molding process, in order to have sufficient molding material available during the compression molding, larger amounts of molding material are needed. Alternatively, the finished substrate has less cured molding material than is desirable.
Thus, there has been a need for a fiber web material which is more pliable and easily drapable within a mold so as to produce sharper corners and better undercut or straight wall areas and which carries a maximum amount, within desired limits, of uncured molding material. The invention herein is concerned with such a web and a method of forming it, which results in a more pliable, drapable, web that can be more deeply and easily drawn in a compression molding operation.